Environment Influences Functional Outcome of Cerebral Infarction in Rats

Abstract

The purpose of this study was to determine whether preoperative and postoperative enrichment of the environment can enhance the functional outcome after cerebral infarction in rats. The right middle cerebral artery was ligated in adult spontaneously hypertensive male rats, and the functional outcome was studied for 12 weeks after the operation. Three groups were compared: A, rats kept in individual cages before and after the operation (n = 9); B, rats kept in individual cages before the operation but transferred to an enriched environment after the operation (n = 10); and C, rats kept in an enriched environment all the time (n = 12). The enriched environment consisted of a large cage with opportunities for various activities, but rats were not forced to do any particular tasks. Rats kept in an enriched environment (groups B and C) performed significantly better than rats in group A in a leg-placement test, beam walking, walking on a rotating pole, and climbing. The infarct size and thalamic atrophy did not differ among the groups. The laboratory environment is important for the functional outcome in brain ischemia. We hypothesize that an enriched environment may stimulate mechanisms that enhance brain plasticity after focal brain ischemia.